The book deals with nitrate determine in environmental matrices and food products. A simple and sensitive Reversed Phase Ion Pair High Performance Liquid Chromatography (RP-IP- HPLC) method for the determination of nitrate has been developed. The determination of nitrate concentration was carried out on HPLC (Waters) coupled with UV detector, using reversed phase chromatography technique. Investigations were performed using mobile phase comprising 80% tetra-ethyl ammonium chloride (6.0 mM) and 20 % pure acetonitrile (HPLC grade). Separation was done by reversed phase C18 column (150mm 4.5mm i.d., 5μm particle size, waters, Canada) with flow rate of 0.5mL/min at optimized wavelength of 210 nm in isocratic mode. Nitrate peak was eluted at 3.2 minutes. The book also contain results of case study which ws carried out on groundwater, rain water and food samples. The book will prove to be an asset in environmental chemistry.